pgsql: Don't leave roles behind after core regression tests.

Don't leave roles behind after core regression tests.

Commits cf5eb37c5 and e5b8a4c09 each created a new role that they
forgot to remove again. This breaks the use-case of running "make
installcheck" more than once, and it's also against project policy
because it'd be quite unfriendly behavior if one were running
"make installcheck" against a non-throwaway installation.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d0d968328794a25c844dc57585d0289a08159bb5

Modified Files
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src/test/regress/expected/create_role.out | 7 ++++++-
src/test/regress/sql/create_role.sql | 6 +++++-
2 files changed, 11 insertions(+), 2 deletions(-)